The goal of this project has been to identify a reliable and cost-effective pre-treatment methodology for use in processes employed to treat and reuse field-produced brine and fracture flowback waters. The objective was to develop a mobile, multifunctional water treatment capability designed specifically for “pre-treatment” of field waste brine by conducting a side-by-side comparison between this new technology and technology already being used in field operations.
Texas A&M University
Argonne National Laboratory
Los Alamos National Laboratory
Houston Advanced Research Center
Sam Houston State University
Rensselaer Polytechnic Institute
New York State Research Development Authority (NYSERDA)
BG Exco Partnership
Shale gas development relies heavily on the hydraulic fracturing process in order to maximize the economic viability of each new well. Many new wells are horizontal wells that require up to 10 million gallons of water (typically fresh water) for each frac job. Not all regions of the country possess sufficient unallocated fresh water resources to fulfill the “new water” requirements needed for each frac job. Additionally, there are numerous regulatory agency/community questions and concerns—particularly with respect to the safety of the hydraulic fracturing process and its potential to harm the environment—regarding the development of these new areas. It is clear that the human dimension of the challenge of developing Marcellus gas resources cannot be neglected.
The challenge is to identify technologies and approaches for treating the frac water that returns to the surface following a frac job (frac flowback water) for beneficial re-use in other applications, thereby conserving other local freshwater supplies. One important application would be to treat the water so that it could be reused in subsequent frac jobs. The demonstration of such technologies in field applications is needed to provide industry, policy makers, and the public with the information they need to make better decisions regarding the development of critical energy resources.
This project consisted of eight (8) tasks that demonstrate frac water pre-treatment technology in field operations. Successful completion of these tasks will prove the ability of this technology to remove constituents from the high salinity flowback water and produced brines encountered in the Marcellus region—and accomplish this with minimal chemical usage and no adverse environmental impact.
Intermediate results from pilot plant tests and field trials with ultra-high salinity brine reveal that properly designed membrane processes are imminently practical. Of all the technologies being implemented in the Marcellus Shale and other gas shale areas, membrane technology offers the most promise at the least cost and greatest efficiency.
Re-use of frac flowback water and produced brine is a key to the successful development of shale natural gas resources. The ability to cost-effectively treat and reuse flowback water for future frac jobs will greatly mitigate problems associated with fresh water usage in shale gas wells. Further, pre-treatment of frac flowback brine is essential in the Marcellus Shale region due to the limited availability of deep well disposal facilities for handling discharged brine. The specific benefits of this project will be realized when field evaluations employing different, highly-mobile pre-treatment technologies, demonstrate the ability to convert highly saline flowback water to a moderate salinity.
Researchers identified the best technologies for deployment in the field and have conducted a month-long trial in upstate New York. This trial processed ultra-high salinity brine of greater than 140,000 total dissolved solids, removing all hydrocarbons and bacteria from produced water and removing all suspended solids so that nanofiltration using spiral wrapped polymeric membranes was able to remove divalent dissolved ions, making the produced water thermodynamically stable and suitable for re-use in subsequent well operations.
Pretreatment technologies for field operations deployment have been identified. Tests have been replicated at three locations where all results have validated performance of the pre-filtration process train to determine operating cost, separation efficiency, and product water quality. The power cost to operate the pre-treatment process has ranged from $.84 to $1.12 per barrel of treated brine. These costs validate the expectation that offending contaminants can be removed from flowback brine and produced water at very reasonable rates.
The chief accomplishment has been the development of a “chemicals free” methodology for removing contaminants from highly saline oil field produced brine. This accomplishment promises a more environmentally friendly way to manage produced and frac water flowback from Marcellus gas shale drilling.
The project has been completed. The final report is available below under "Additional Information".
All three field trials planned for in the deliverables have been completed. One test (Chenango Co, NY) was performed in the fall of 2011. Two additional tests have been performed in Pennsylvania: one in Washington Co. and the other in Armstrong Co.
The final goal of the project has been met. Treatment has shown ultra-high salinity brines could be effectively treated to remove contaminants. Three types of hydrocarbon removal media were evaluated. Four types of micro-filters were tested and three types of nano-filtration performed.
The project results show that suspended solids contamination could be removed by membrane processing rather than traditional means. Nanofiltration showed that the ultra-high salinity brine, normally prone to scale formation, could be treated to remove offending scalants to make a stable solids-free brine suitable for adding to frac make-up water.